<?php
 /**
 * Univarsel Feed Writer class
 *
 * Genarate RSS 1.0, RSS2.0 and ATOM Feed
 *
 * @package     Feed
 * @link        http://www.ajaxray.com/projects/rss
 */

/** Tinyask_Feed_Item */
require_once 'tinyask/feed/item.php';

class Tinyask_Feed_Writer
{
	private $channels      = array();  // Collection of channel elements
	private $items         = array();  // Collection of items as object of Typecho_Feed_Item class.
	private $data          = array();  // Store some other version wise data
	private $CDATAEncoding = array();  // The tag names which have to encoded as CDATA

	private $version   = null;

	/**
	 * 字符集
	 *
	 * @var string
	 */
	private $charset   = 'UTF-8';

	/**
	* Constructor
	*
	* @param    constant    the version constant (RSS1/RSS2/ATOM).
	*/
	function __construct($version = Tinyask_Feed::RSS2)
	{
		$this->version = $version;

		// Setting default value for assential channel elements
		$this->channels['title']        = $version . ' Feed';
		$this->channels['link']         = 'http://www.ajaxray.com/blog';

		//Tag names to encode in CDATA
		$this->CDATAEncoding = array('description', 'content:encoded', 'summary', 'title', 'author', 'dc:creator', 'category');
	}

	/**
	* Set a channel element
	*
	* @param    srting  name of the channel tag
	* @param    string  content of the channel tag
	*/
	public function setChannelElement($elementName, $content)
	{
		$this->channels[$elementName] = $content ;
	}

	/**
	* Set multiple channel elements from an array. Array elements
	* should be 'channelName' => 'channelContent' format.
	*
	* @param    array   array of channels
	*/
	public function setChannelElementsFromArray($elementArray)
	{
		if (! is_array($elementArray)) {
			return;
		}
		foreach ($elementArray as $elementName => $content) {
			$this->setChannelElement($elementName, $content);
		}
	}

	/**
	* Generate the actual RSS/ATOM file
	*
	*/
	public function generateFeed()
	{
		header("Content-type: text/xml; charset=" . $this->charset, true);

		$this->printHead();
		$this->printChannels();
		$this->printItems();
		$this->printTale();
	}

	/**
	* Create a new Tinyask_Feed_Item.
	*
	* @return   object  instance of Tinyask_Feed_Item class
	*/
	public function createNewItem()
	{
		$Item = new Tinyask_Feed_Item($this->version);
		return $Item;
	}

	/**
	* Add a Tinyask_Feed_Item to the main class
	*
	* @param    object  instance of Typecho_Feed_Item class
	*/
	public function addItem($feedItem)
	{
		$this->items[] = $feedItem;
	}

	/**
	 * 设置字符集
	 *
	 * @param string $charset 字符集
	 */
	public function setCharset($charset)
	{
		$this->charset = $charset;
	}

	/**
	* Set the 'title' channel element
	*
	* @param    srting  value of 'title' channel tag
	*/
	public function setTitle($title)
	{
		$this->setChannelElement('title', $title);
	}

	/**
	* Set the 'subtitle' channel element
	*
	* @param    srting  value of 'title' channel tag
	*/
	public function setSubTitle($subtitle)
	{
		$this->data['subtitle'] = $subtitle;
	}

	/**
	* Set the 'description' channel element
	*
	* @param    srting  value of 'description' channel tag
	*/
	public function setDescription($desciption)
	{
		$this->setChannelElement('description', $desciption);
	}

	/**
	* Set the 'link' channel element
	*
	* @param    srting  value of 'link' channel tag
	*/
	public function setLink($link)
	{
		$this->setChannelElement('link', $link);
	}

	/**
	* Set the 'image' channel element
	*
	* @param    srting  title of image
	* @param    srting  link url of the imahe
	* @param    srting  path url of the image
	*/
	public function setImage($title, $link, $url)
	{
		$this->setChannelElement('image', array('title'=>$title, 'link'=>$link, 'url'=>$url));
	}

	/**
	* Set the 'about' channel element. Only for RSS 1.0
	*
	* @param    srting  value of 'about' channel tag
	*/
	public function setChannelAbout($url)
	{
		$this->data['ChannelAbout'] = $url;
	}

	/**
	* Genarates an UUID
	* @author     Anis uddin Ahmad <admin@ajaxray.com>
	* @param      string  an optional prefix
	* @return     string  the formated uuid
	*/
	public static function uuid($key = null, $prefix = '')
	{
		$key = ($key == null)? uniqid(rand()) : $key;
		$chars = md5($key);
		$uuid  = substr($chars,0,8) . '-';
		$uuid .= substr($chars,8,4) . '-';
		$uuid .= substr($chars,12,4) . '-';
		$uuid .= substr($chars,16,4) . '-';
		$uuid .= substr($chars,20,12);

		return $prefix . $uuid;
	}

	/**
	* Prints the xml and rss namespace
	*
	*/
	private function printHead()
	{
		$out  = '<?xml version="1.0" encoding="' . $this->charset . '"?>' . Tinyask_Feed::EOL;

		if ($this->version == Tinyask_Feed::RSS2) {
			$out .= '<rss version="2.0"
xmlns:content="http://purl.org/rss/1.0/modules/content/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:slash="http://purl.org/rss/1.0/modules/slash/"
xmlns:wfw="http://wellformedweb.org/CommentAPI/">' . Tinyask_Feed::EOL;
		} elseif ($this->version == Tinyask_Feed::RSS1) {
			$out .= '<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://purl.org/rss/1.0/"
xmlns:dc="http://purl.org/dc/elements/1.1/">' . Tinyask_Feed::EOL;;
		} else if ($this->version == Tinyask_Feed::ATOM1) {
			$out .= '<feed xmlns="http://www.w3.org/2005/Atom">' . Tinyask_Feed::EOL;;
		}
		echo $out;
	}

	/**
	* Closes the open tags at the end of file
	*
	*/
	private function printTale()
	{
		if ($this->version == Tinyask_Feed::RSS2) {
			echo '</channel>' . Tinyask_Feed::EOL . '</rss>';
		} elseif ($this->version == Tinyask_Feed::RSS1) {
			echo '</rdf:RDF>';
		} else if ($this->version == Tinyask_Feed::ATOM1) {
			echo '</feed>';
		}

	}

	/**
	* Creates a single node as xml format
	*
	* @param    srting  name of the tag
	* @param    mixed   tag value as string or array of nested tags in 'tagName' => 'tagValue' format
	* @param    array   Attributes(if any) in 'attrName' => 'attrValue' format
	* @return   string  formatted xml tag
	*/
	private function makeNode($tagName, $tagContent, $attributes = null)
	{
		$nodeText = '';
		$attrText = '';

		if (is_array($attributes)) {
			foreach ($attributes as $key => $value) {
				$attrText .= " $key=\"$value\" ";
			}
		}

		if (is_array($tagContent) && $this->version == Tinyask_Feed::RSS1) {
			$attrText = ' rdf:parseType="Resource"';
		}


		$attrText .= (in_array($tagName, $this->CDATAEncoding) && $this->version == Tinyask_Feed::ATOM1)? ' type="html" ' : '';

        if (empty($tagContent)) {
            $nodeText .= "<{$tagName}{$attrText}";
        } else {
            $nodeText .= (in_array($tagName, $this->CDATAEncoding)) ? "<{$tagName}{$attrText}><![CDATA[" : "<{$tagName}{$attrText}>";
        }

		if (is_array($tagContent)) {
			foreach ($tagContent as $key => $value) {
				$nodeText .= $this->makeNode($key, $value);
			}
		} else {
			$nodeText .= (in_array($tagName, $this->CDATAEncoding))? $tagContent : htmlentities($tagContent);
		}

        if (empty($tagContent)) {
            $nodeText .=  "/>";
        } else {
            $nodeText .= (in_array($tagName, $this->CDATAEncoding)) ? "]]></$tagName>" : "</$tagName>";
        }

		return $nodeText . Tinyask_Feed::EOL;
	}

	/**
	* Print channels
	*
	*/
	private function printChannels()
	{
		//Start channel tag
		switch ($this->version) {
		    case Tinyask_Feed::RSS2:
				echo '<channel>' . Tinyask_Feed::EOL;
				break;
		    case Tinyask_Feed::RSS1:
                echo (isset($this->data['ChannelAbout']))? "<channel rdf:about=\"{$this->data['ChannelAbout']}\">" : "<channel rdf:about=\"{$this->channels['link']}\">";
				break;
            case Tinyask_Feed::ATOM1:
                echo (isset($this->data['subtitle']))? '<subtitle type="text">' . $this->data['subtitle'] . '</subtitle>' : NULL;
                break;
		}

		//Print Items of channel
		foreach ($this->channels as $key => $value) {
			if ($this->version == Tinyask_Feed::ATOM1 && $key == 'link') {
				// ATOM prints link element as href attribute
				echo $this->makeNode($key,'',array('href'=>$value));
				//Add the id for ATOM
				echo $this->makeNode('id',$this->uuid($value,'urn:uuid:'));
			} else {
				echo $this->makeNode($key, $value);
			}
		}

		//RSS 1.0 have special tag <rdf:Seq> with channel
		if ($this->version == Tinyask_Feed::RSS1) {
			echo "<items>" . Tinyask_Feed::EOL . "<rdf:Seq>" . Tinyask_Feed::EOL;
			foreach ($this->items as $item) {
				$thisItems = $item->getElements();
				echo "<rdf:li resource=\"{$thisItems['link']['content']}\"/>" . Tinyask_Feed::EOL;
			}
			echo "</rdf:Seq>" . Tinyask_Feed::EOL . "</items>" . Tinyask_Feed::EOL . "</channel>" . Tinyask_Feed::EOL;
		}
	}

	/**
	* Prints formatted feed items
	*
	*/
	private function printItems()
	{
		foreach ($this->items as $item) {
			$thisItems = $item->getElements();

			//the argument is printed as rdf:about attribute of item in rss 1.0
			echo $this->startItem($thisItems['link']['content']);

			foreach ($thisItems as $feedItem) {
				if ('category' == $feedItem['name']) {
					foreach ($feedItem['content'] as $category) {
						if (Tinyask_Feed::ATOM1 == $this->version) {
							echo $this->makeNode('category', NULL, array('scheme' => $category['permalink'], 'term' => $category['name']));
						} else if (Tinyask_Feed::RSS2 == $this->version) {
							echo $this->makeNode('category', $category['name']);
						}
					}
				} else {
					echo $this->makeNode($feedItem['name'], $feedItem['content'], $feedItem['attributes']);
				}
			}
			echo $this->endItem();
		}
	}

	/**
	* Make the starting tag of channels
	*
	* @param    srting  The vale of about tag which is used for only RSS 1.0
	*/
	private function startItem($about = false)
	{
		if ($this->version == Tinyask_Feed::RSS2) {
			echo '<item>' . Tinyask_Feed::EOL;
		} elseif ($this->version == Tinyask_Feed::RSS1) {
			if ($about) {
				echo "<item rdf:about=\"$about\">" . Tinyask_Feed::EOL;
			} else {
				die('link element is not set .\n It\'s required for RSS 1.0 to be used as about attribute of item');
			}
		} else if ($this->version == Tinyask_Feed::ATOM1) {
			echo "<entry>" . Tinyask_Feed::EOL;
		}
	}

	/**
	* Closes feed item tag
	*
	*/
	private function endItem()
	{
		if ($this->version == Tinyask_Feed::RSS2 || $this->version == Tinyask_Feed::RSS1) {
			echo '</item>' . Tinyask_Feed::EOL;
		} else if ($this->version == Tinyask_Feed::ATOM1) {
			echo "</entry>" . Tinyask_Feed::EOL;
		}
	}
}
